1. Field of the Invention
This invention relates to a lubrication apparatus in an internal combustion engine chiefly used for a vehicle.
2. Description of the Prior Art
Prior art lubrication systems are used in which an oil pan is detachably provided on the lower surface of a crank chamber of an internal combustion engine in order to close the crank chamber. An oil pump having an oil intake opening and an oil filter which is in communication with the oil pump through a communication passage are provided in the crank chamber, and the communication passage has a relief valve arranged to be opened by an oil pressure above a predetermined value. Normally, in this type of apparatus, the relief valve is fixed to the pump or the crank chamber by being fastened thereto by means of a screw or the like, and accordingly, this arrangement results in difficulty in attaching and detaching of the relief valve and requires much trouble and nuisance.